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#1
December 7th 05, 09:53 PM
posted to rec.radio.amateur.antenna
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Principles of operation for dual band vertical antenna (2m/70cm)
Hi
Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower portion of the antenna is cut for 70 CM and the entire antenna including the coiled portion is used for two meters? Does all or a portion of the coil add to the length for either frequency? Thanks for your help. Ed AD5JV |
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#2
December 7th 05, 10:41 PM
posted to rec.radio.amateur.antenna
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Principles of operation for dual band vertical antenna (2m/70cm)
Ed Laughery wrote:
Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower portion of the antenna is cut for 70 CM and the entire antenna including the coiled portion is used for two meters? Does all or a portion of the coil add to the length for either frequency? For mine, the coil acts as a loading coil on 2m and a phasing coil on 70cm. -- 73, Cecil http://www.qsl.net/w5dxp |
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#3
December 7th 05, 11:59 PM
posted to rec.radio.amateur.antenna
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Principles of operation for dual band vertical antenna (2m/70cm)
There are several types, so you need to give a better description of the one
you refer to. The "Hershey kiss" one I have looks like a 2M 1/4 wave, but with a small, 3-4 turn coil at the base. It appears to be "5/8" on 440 and "1/4" wave on 2. However, on 440 the 5/8 needs some series inductance to tune out the capacitance of the 5/8. With this inductance in there, the 2M 1/4 wave has un needed loading, so it has to be shortened for a better match. It all fits. The frequency ratio is ~~ 3:4 and 5/8 is less that 3/4, so it is shorter than both 1/4 and 3/4... Better get out the yard stick again and verify my recollection... 73, Steve, K,9.D;C'I "Ed Laughery" wrote in message . .. Hi Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower portion of the antenna is cut for 70 CM and the entire antenna including the coiled portion is used for two meters? Does all or a portion of the coil add to the length for either frequency? Thanks for your help. Ed AD5JV |
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#4
December 8th 05, 01:25 AM
posted to rec.radio.amateur.antenna
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Principles of operation for dual band vertical antenna (2m/70cm)
I think the Larsen operates as a loaded 2 meter, 1/2 wavelength
equivalent, and as a 2 elrment collinear on 440. Ed Laughery wrote: Hi Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower portion of the antenna is cut for 70 CM and the entire antenna including the coiled portion is used for two meters? Does all or a portion of the coil add to the length for either frequency? Thanks for your help. Ed AD5JV |
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